AllowEncrypted is defined on the client end, via the WSMAN: drive. You must be running powershell.exe (or powershell_ise.exe) as an elevated process.
ps> cd WSMan:\localhost\Client
ps> dir
Name Value
---- -----
NetworkDelayms 5000
URLPrefix wsman
AllowUnencrypted false
Auth
DefaultPorts
TrustedHosts
You would change it like so (after changing to the directory above):
Set-Item .\allowunencrypted $true
Hope this helps,
- Oisin